Objective To observe the effect of electroacupuncture(EA) and manual acupuncture(MA) on learning-memory ability

changes of ultrastructure of neurons and expression of CDK5 and Tau proteins in hippocampus of SAMP8 mice

so as to explore its mechanisms underlying improvement of Alzheimer's disease(AD).Methods A total of 45 male SAMP8 mice were randomly divided into model

EA and MA groups

with 15 mice in each group. The other 15 SAMR1 mice were used as the normal group. In the EA group

EA(2 Hz

1 mA) was applied to bilateral "Shenshu"(BL23) and manual acupuncture was applied to "Baihui"(GV20) for 20 min. In the MA group

MA was applied to GV20 and bilateral BL23 for 20 min. Both group were treated once a day for 31 days

and with an interval of one day between every two 7 days. Morris water maze was performed to assess the animals' learning-memory ability. The morphological changes of hippocampal neurons were observed under transmission electron microscopy. The expression levels of CDK5

p25 and Tau-5 proteins in the hippocampus were detected by immunohistochemistry and Western blot

separately.Results ①Compared with the normal group

the average escape latency of Morris water maze test was prolonged in the model group(P<0.05

P<0.01)

duration of swimming in the original platform quadrant and the number of original platform crossing were significantly shorter and less respectively(P<0.01). Compared with the model group

the average escape latency in the EA group was shortened(P<0.05

P <0.01)

the duration of swimming in the original platform quadrant and the number of original platform crossing were significantly prolonged and increased(P<0.01); The average escape latency in the MA group was shortened(P<0.05

P <0.01)

and the duration of swimming in the original platform quadrant was prolonged(P<0.05). Compared with the EA group

the average escape latency of the MA group was prolonged(P<0.05)

the duration of swimming in the original platform quadrant was shortened(P<0.05). ②Transmission electron microscopy revealed that the neurons in the hippocampal CA1 area had irregular shape and vague structure

reduction in size and number of mitochondria accompanied with swelling

and malformed changes of mitochondrial crest in the model group

which was relatively milder in both EA and MA groups. ③The expression levels of hippocampal Tau-5

p25 and CDK5 proteins were significantly up-regulated in the model group in contrast to the normal group(P<0.01

P<0.05)

and obviously down-regulated in both EA and MA groups relevant to the model group(P<0.05

P<0.01). Compared with the EA group

the expression levels of p25 and CDK5 proteins were significantly increased in the MA group(P<0.05). Conclusion EA of BL23 can improve the learning-memory ability in SAMP8 mice

which is associated with its effect in down-regulating the expression of hippocampal CDK5

p25 and Tau-5 proteins.